1. Field of the Invention
The present invention relates to the art of position sensors, and more particularly to position sensors intended to measure the torsion of a steering column, although such an application is not exclusive.
2. Description of the Related Art
In the prior art there is known U.S. Pat. No. 4,984,474, which describes a prior art sensor provided with a stator part comprising a ferromagnetic piece forming radial teeth at two levels, disposed facing multi-pole magnets that are radially magnetized in alternating directions.
An additional ferromagnetic piece is disposed facing the stator part, and forms an air gap in which there is placed a Hall probe.
This prior art solution is not satisfactory, because it leads to a loss of magnetic signal between the stator part and the part containing the Hall probe. Furthermore, the magnetic field generated by the magnets leads to losses due to the sensor structure.
Also known in the prior art is a sensor described in U.S. Pat. No. 4,784,002, which describes another position sensor comprising a part provided with a plurality of axially oriented magnets cooperating with radial teeth of a stator part.
This structure also leads to magnetic leaks and to reduced efficiency, manifested by a poor “signal-to-noise” ratio.